The present invention relates to characterization of particles and, more particularly, to methods and systems for particle characterization using an optical sensor output signal.
Particle sensing has many applications. One application is respiratory disease alerts. Exposure to airborne particles is closely associated with respiratory ailments, such as asthma, bronchitis and respiratory infections. Thus, early detection and alerting of a patient of airborne particles can allow the patient to take a respiratory health-preserving action (e.g. evacuation of an area with high particle density) and reduce the incidence and severity of respiratory afflictions. Other applications for particle sensing include biological cell identification, worker protection in dusty environments and ocean water analysis.
Portable monitors that sense and report in real-time on the presence of airborne particles in the vicinity of a patient are known. These portable monitors often take continual light scattering measurements that detect the presence of airborne particles and notify the patient who is wearing the monitor of particle presence. While such portable monitors inform about the presence of airborne particles, they are not known to characterize airborne particles, such as by providing information on particle density, size and type. The lack of airborne particle characterization leaves the patient and his or her health care provider without information required to make optimal respiratory health-preserving decisions. For example, for a given respiratory disease or patient, a different health-preserving action may be indicated depending on the type of a detected particle (e.g. smoke, dust, pollen, etc.) or whether the detected particle is large or small.
Advanced optical sensors that characterize airborne particles are known. These advanced sensors often take light scattering measurements at multiple wavelengths and/or multiple angles to generate a large body of scattered light data. The body of light scattering data is then applied to a database to obtain fitted results concerning particle size and/or type. Accordingly, these advanced sensors require substantial overhead and are typically not suitable for use in portable monitors.